[Nouveau] [PATCH 2/3] drm/nouveau/kms/nv50-: Report max cursor size to userspace

[James Jones]

On 3/3/21 8:51 AM, Lyude Paul wrote:
> On Wed, 2021-03-03 at 08:12 -0500, Ilia Mirkin wrote:
>> On Wed, Mar 3, 2021 at 7:41 AM Alex Riesen <alexander.riesen at cetitec.com>
>> wrote:
>>>
>>> Ilia Mirkin, Sat, Feb 27, 2021 22:26:57 +0100:
>>>> Can you try Alex's patch to modetest and confirm that you see issues
>>>> with modetest? If so, can you (and maybe Alex as well) try an older
>>>> kernel (I'm on 5.6) and see if modetest behaves well there. [The patch
>>>> in question was to expose 256x256 as the 'preferred' size, but support
>>>> for the larger cursors has been around for a while.] Alex - if you
>>>> have time, same question to you.
>>>
>>> Sorry that it took so long. I retestet with the same kernel as Uwe did
>>> (5.4.101) and my results are the same: modetest with 64 and 128 cursors
>>> looks
>>> good, 256 broken. Didn't test with X this time (this being my main office
>>> machine), but can do later if required.
>>
>> Thanks for confirming! No need to test X - that will work fine, since
>> we were reporting the smaller cursors on that kernel.
>>
>> So I think we have definitive evidence that at least all Kepler
>> doesn't do 256x256 (and it's not just some bug in the display macro
>> rework that got introduced). And unless I'm blind and don't see the
>> corruption, Pascal seems fine. Question remains for Maxwell1/2 GPUs.
>> Unless someone has immediate plans to test on those, I'd recommend
>> bumping the minimum for 256x256 being reported to Pascal, and doing
>> 128x128 for Kepler / Maxwell.
> 
> I'm fairly sure this will actually work fine on maxwell, I think Kepler is the
> only one I'm aware of so far that has issues with this. I've got one of each gen
> from kepler 1 up to ampere, so I'll try to find some today to test the cards
> I've got and see where the support cutoff for this is and then submit a patch
> for the time being.
> 
> It's also really strange to me that this would be present in the display classes
> yet not be supported on the GPU, since there definitely aren't any capabilities
> for this. I'll also send an email to Andy and see if he might know what's going
> on here.

FWIW, it's not my area, but I've been following, and forwarded this 
thread around internally.  We discussed a bit, and Kepler definitely 
supports 256x256 cursors. One suggestion was if you aren't already, try 
using 4k pages. The rest was a bit beyond me, so I'll let Andy and Lyude 
discuss further if needed.

Thanks,
-James

>> Simon, Lyude -- thoughts?
>>
>> Cheers,
>>
>>    -ilia
>>
>